Our intrepid reporter gets up close and personal with New Guinea natives who say they still eat their fellow tribesmen.

My three days with the clan pass swiftly. When I feel they trust me, I ask when they last killed a khakhua. Lepeadon says it was near the time of the last sago palm feast, when several hundred Korowai gathered to dance, eat vast quantities of sago palm maggots, trade goods, chant fertility songs and let the marriage-age youngsters eye one another. According to our porters, that dates the killing to just over a year ago.

Lepeadon tells Boas he wants me to stay longer, but I have to return to Yaniruma to meet the Twin Otter. As we board the pirogue, the fierce man squats by the riverside but refuses to look at me. When the boatmen push away, he leaps up, scowls, thrusts a cassowary-bone arrow across his bow, yanks on the rattan string and aims at me. After a few moments, he smiles and lowers the bow—a fierce man's way of saying goodbye.

In midafternoon, the boatmen steer the pirogue to the edge of a swamp forest and tie it to a tree trunk. Boas leaps out and leads the way, setting a brisk pace. After an hour’s trek, I reach a clearing about the size of two football fields and planted with banana trees. Dominating it is a treehouse that soars about 75 feet into the sky. Its springy floor rests on several natural columns, tall trees cut off at the point where branches once flared out.

Boas is waiting for us. Next to him stands his father, Khanduop, a middle-aged man clad in rattan strips about his waist and a leaf covering part of his penis. He grabs my hand and thanks me for bringing his son home. He has killed a large pig for the occasion, and Bailom, with what seems to me to be superhuman strength, carries it on his back up a notched pole into the treehouse. Inside, every nook and cranny is crammed with bones from previous feasts—spiky fish skeletons, blockbuster pig jaws, the skulls of flying foxes and rats. The bones dangle even from hooks strung along the ceiling, near bundles of many-colored parrot and cassowary feathers. The Korowai believe that the décor signals hospitality and prosperity.

I meet Yakor, a tall, kindly eyed tribesman from a treehouse upriver, who squats by the fire with Khanduop, Bailom and Kilikili. Boas’ mother is dead, and Khanduop, a fierce man, has married Yakor's sister. When the talk turns to khakhua meals they have enjoyed, Khanduop's eyes light up. He's dined on many khakhua, he says, and the taste is the most delicious of any creature he's ever eaten.

The next morning the porters depart for the river, carrying our remaining supplies. But before I leave, Khanduop wants to talk; his son and Kembaren translate. "Boas has told me he'll live in Yaniruma with his brother, coming back just for visits," he murmurs. Khanduop's gaze clouds. "The time of the true Korowai is coming to an end, and that makes me very sad."

Boas gives his father a wan smile and walks with me to the pirogue for the two-hour journey to Yaniruma, wearing his yellow bonnet as if it were a visa for the 21st century.

Three years earlier I had visited the Korubo, an isolated indigenous tribe in the Amazon, together with Sydney Possuelo, then director of Brazil's Department for Isolated Indians [SMITHSONIAN, April 2005]. This question of what to do with such peoples—whether to yank them into the present or leave them untouched in their jungles and traditions—had troubled Possuelo for decades. "I believe we should let them live in their own special worlds," he told me, "because once they go downriver to the settlements and see what is to them the wonders and magic of our lives, they never go back to live in a traditional way."

So it is with the Korowai. They have at most a generation left in their traditional culture—one that includes practices that admittedly strike us as abhorrent. Year by year the young men and women will drift to Yaniruma and other settlements until only aging clan members are left in the treehouses. And at that point Ginol's godly prophecy will reach its apocalyptic fulfillment, and thunder and earthquakes of a kind will destroy the old Korowai world forever.